Background: A firm mattress is commonly believed to be beneficial for low-back pain, although evidence supporting this recommendation is lacking. We assessed the effect of different firmnesses of mattresses on the clinical course of patients with chronic non-specific low-back pain.
Methods: In a randomised, double-blind, controlled, multicentre trial, we assessed 313 adults who had chronic non-specific low-back pain, but no referred pain, who complained of backache while lying in bed and on rising. Mattress firmness is rated on a scale developed by the European Committee for Standardisation. The H(s) scale starts at 1.0 (firmest) and stops at 10.0 (softest). We randomly assigned participants firm mattresses (H(s)=2.3) or medium-firm mattresses (H(s)=5.6). We did clinical assessments at baseline and at 90 days. Primary endpoints were improvements in pain while lying in bed, pain on rising, and disability.
Findings: At 90 days, patients with medium-firm mattresses had better outcomes for pain in bed (odds ratio 2.36 [95% CI 1.13-4.93]), pain on rising (1.93 [0.97-3.86]), and disability (2.10 [1.24-3.56]) than did patients with firm mattresses. Throughout the study period, patients with medium-firm mattresses also had less daytime low-back pain (p=0.059), pain while lying in bed (p=0.064), and pain on rising (p=0.008) than did patients with firm mattresses.
Interpretation: A mattress of medium firmness improves pain and disability among patients with chronic non-specific low-back pain.